Earthquake Building Technology

Soils and Foundations, Earthquake Effects and Resisting Features

Type of soil

Damaging Effect of Earthquake

Earthquake Resisting Feature

Type I Hard

None

Use any foundation type

Type II Medium

Not much in Zones II and III.
Relative lateral movement possible in Zones IV, V.
Use any foundation type.
Use tie beams in case of individual column foundations.

Type III soft

a. Low water table

Not much in Zone II.
Relative lateral movement possible in Zone III to V

Use any foundation type. Use plinth Band.
Use tie beams to connect individual column foundations or combined column footings or provide rafts or piles as needed for the loads.

b. Liquefiable with high water table

Some relative movement in Zone II.
Relative lateral and vertical movements possible in Zone III.
Liquefaction resulting in tilting/overturning of buildings and structures likely in Zones IV & V
Use plinth beams/tie beams to connect individual column foundations

Use piles going to stable soil layer or minimum 10m length. Driven piles preferable

    Or

Improve the soil to a depth of 7 to 8 m or upto stable layer if met earlier, by dynamic compaction or by compaction piles.

c. Black cotton soil

Spoil not seen to be affected in intensity VIII shaking in Latur or Jabalpur earthquakes, but effect of ground motion amplified on the buildings

Use B1.2 or 1.5 in determining a, for building category in Table 7.
Use tie beams to connect individual column footings. Use plingh bank in case of strip foundations.
Use of under-ream piles preferable.

Building Walls, Earthquake Effects and Resisting Features*

Type of soil

Damaging Effect of Earthquake

Earthquake Resisting Feature

All masonry walls

(with flat roofs)

  1. Shattering of masonry in heap of materials.
  2. Cracking and separation of walls of corners and functions of walls.
  3. Diagonal cracking in piers between windows and doors.
  4. Vertical bending cracks near tope of walls.
  5. Horizontal cracks near base of storeys.
  • Use of good quality building units, cement sand or cement-lime-sand mortar, good quality of construction.
  • Use of lintel band, in all internal and external walls with continuity in the reinforcement.
  • Control on size and location of openings and use of reinforcing bars at jambs.
  • Use of ceiling level band(like lintel band) below the roof or floor.
  • Use of vertical reinforcing bars at corners and junctions of walls.

All masonry walls

(with pitched roofs)

Besides (a.) to (e.) above

f. Cracking and falling of gable walls.

  • Use bands at eave level in all walls and on tope of all gable walls integrated with the eave bands.

Random rubble masonry walls

Besides (a.) to (f.) above.

g. Delamination of inner and outer wythes of the wall, bulging and falling of wythes

  • Use of walls not thicker than 450 mm with provision of ‘through’stones or bonding elements in the walls and at the corners & T-joints.(use of good cement mortar reduces chances of delamination).

Wood stud wall

h. Deforms and collapses

  • Use ‘sill’ held down to footings by bolts, diagonal braces in vertical plane of walls and in the horizontal plane at tope of wall connecting to perpendicular wall.

Wood frame with brick nogging

i. Brick nogging falls out of wall

j. Deformation of wood frame

  • Use hold-fasts to hold the nogging.
  • Use diagonal braces in vertical and horizontal plans as for wood-stud swall construction.

Clay/Adobe/

Unburnt brick walls

  1. Shaking of walls in heap of material.
  2. Cracking and separation at corners
  3. Wide cracking and instability of piers between openings.
  4. Overturning of walls
  • Use better quality clay to make abode and clay mortar, also control on wall length and height.
  • Use lintel band in all walls with continuity between perpendicular walls.
  • Control on size and location of openings.
  • Use of pilasters in long walls and at corners and T-junctions of walls.

Building Roofs and Floors, Earthquake Effects and Resisting Features*

Type of soil

Damaging Effect of Earthquake

Earthquake Resisting Feature

Raftered Roof

  • Rafters are displaced and fall down, damage walls by pulling and pushing

Use full trusses or A-frame arrangement by connecting rafters in pairs through times

Trussed Roof

  • Anchors broken, gables pushed out and damaged, trusses shift and fall down
  • Failures of truss joints in wooden trusses
  • Long walls are topped since without lateral support at top.
  • Provide X-bracings in planes of raftrers in about every 4th bay, and in hortizontal plane of main times in similar bays.
  • Provide adequate iron straps on wood truss joints.
  • Provide eave level trussed bracing in long rooms in addition to eave level band to provide diaphragm action.

Sloping roof using RC Prefab elements

  • The prefab elements are disturbed, separated and may fall down.
  • Connect the elements together and hold them to peripheral R.C. banks.

Beams/Joints supporting stone pattis, or prefab PC or RC elements

  • The prefab elements and the beams/joists are disturbed, the elements may fall down, beams fall down if bear5ing length is small.
  • Keep the bearing length or beams at least 200 mm, integrate the roofing elements by a RC screed, the whole roof/floor bounded by RC band.

Jack arches resting on Steel girders

  • The arches are cracked longitudinally, tend to shift the girders horizontally and may fall down
  • Girders may fall down by slipping longitudinally
  • Weld lateral, lies with all steel girders and embed into RC band provided all round.
  • Weld diagonal braces to steel girders to convert the roof/floor into a horizontal grillage.
  • Encase ends of steel girders into all round RC band.

Tiled roofs

Tiles are disturbed, broken and fall down

  • Use tiles with lug having holds and time them to purlins by binding wire.

*The damaging effects of earthquakes become more and more severe as the intensity increases from VII to IX. Correspondingly the provisions of the resisting features should increase for adequate safety.

For further details kindly contact the following:-

Dr. T.N. Gupta,
Executive Director, Building Materials & Technology Promotion Council,
G-Wing, Nirman Bhavan, New Delhi-110011.
Tel: 91-11-3019367, Fax:91-11-3010145

Dr. V. Suresh,
C.M.D., HUDCO Corporate Office, HUDCO Bhavan,
 India Habitat Centre, Lodhi Road, New Delhi-110003.